In washing machines for domestic use, the detergent is usually manually introduced into a chamber and flushed with water into the suds container after the wash cycle has started. The user must observe the dosage instructions for the particular detergent used, and take care to fill the correct amount into the chamber. To facilitate charging with detergent or other additives, such as fabric softeners, automatic dispensing systems in which a relatively large amount of detergent is stored in a supply container may be used. Once a wash cycle is started, the preset amount of detergent will then be added to the wash liquid, which eliminates the need for the user to ensure that the proper amount of detergent is filled in each time a wash cycle is carried out. Such dispensing systems are frequently used especially in industrial washing machines.
German document DE 39 01 686 A1 describes a washing machine having a dispensing system for liquid detergents, in which the type of treating agent can be preset. In that document, a pump pumps the treating agent, which may, for example, be liquid detergent, from the supply container into the suds container, the user having to preset the amount to be dispensed. When the user fills the supply container with fabric softener in place of detergent, he/she must inform the controller accordingly by operating a lever, so that the treating agent will not be pumped into the suds container until the rinse step.
Another dispensing system for liquid additives is a Miele washing machine named W 4449 Liquid Wash, which has been sold since the beginning of 2006. In that washer, a supply container for liquid detergents is located outside the washing machine and connected thereto via a hose line. Disposed within the washing machine is the metering pump, which delivers the liquid or viscous detergent through a hose line to the lower region of the suds container. The metering pump is controlled by the washing machine controller which, based on the ON-time, determines the amount of detergent to be dispensed at any one time. A reference amount is preset in accordance with the detergent manufacturer's dosage instructions. In order to activate the automatic dispensing feature, the user sets the soil level, and operates an additional control handle, the soil level setting being taken into account when determining the amount of detergent to be dispensed.
DE 10 2006 009 807 A1 describes that a treating agent for a washing machine can be mixed individually. To this end, the washing machine includes a dispensing system in which the individual active substances are stored in separate containers. The dispensing system operates such that, at any one time, a particular treating agent is mixed from a plurality of individual active substances, and dispensed into the suds container, according to the soil level and the type of laundry to be washed. A method involving such a level of complexity is not very suitable in a domestic environment, because the manufacture or mixing of detergents from individual active substances is a task which only a particularly qualified person can be expected to accomplish.
European document EP 1 318 225 A1 describes a dispensing system in which the treating agents are delivered to the washing machine according to the status of the wash cycle. To this end, the time or wash cycle status at which a particular agent is dispensed is permanently defined, resulting in a fixed association of the respective agents.
These methods of operating a dispensing system require the user to consciously activate the dispensing system or, alternatively, to fill the detergent compartment with detergent or treating agent, prior to activating the wash cycle. To do this, the user must always know, and take into account, which detergent is suitable for a particular load of laundry to be washed.